According to the state Department of Education, about 100,000 of the state's 430,000 kids start kindergarten before their 5th birthday.
Three-year-old Morgan Johnson could be forced to start kindergarten later if Gov. Arnold Schwarzenegger signs SB 1381 into law.
"She's an October birthday, so I was hoping that she would go in at 4 so she would be on the same age level as her classmates, not a year older," said parent Nicole Harris Johnson about her daughter Morgan.
"As a parent that really wants the best education and challenges for my son, the earlier that they can go to school, the better in my case and not later," said another parent, Michael Abare.
The move could save the state approximately $700 million a year.
The Los Angeles Unified School District calls it a win-win situation.
"In this bill as it now stands, it will be the same funding for the traditional kindergarten program, so this will have no negative financial impact on the district but would simply allow us to provide us more appropriate services for the right age group," said Whitcomb Hayslip with LAUSD.
Currently, California is one of only four states in the nation with an enrollment date later than Dec. 1. The other states are Connecticut, Michigan and Vermont.
Some advocates say that younger children would do better to spend an extra year in preschool. Opponents say that kids need more in-school education and not less.
"I understand the state wanting to save money, but I'm sure if we wanted to, we can find other means to get him to go to school before the state would allow us to, so to speak," said Kirk Woller, a parent.
The new law would not take effect immediately. Senate Bill 1381 would be phased in over three years starting in the 2012-13 school year.
The Associated Press contributed to this report.